Polished rod with latching section

ABSTRACT

A polished rod for supporting a sucker rod string comprising a one piece shank with an upper end and a lower end. A first connector is formed on the upper end of the shank and a second connector is formed on the lower end of the shank. The shank has a sealing section extending from the lower end toward the upper end and the sealing section has a polished surface and a uniform cylindrical diameter substantially equal to the diameter of the upper end and the lower end of the shank. The shank further has a latching section formed between the sealing section and the upper end. The latching section of the shank has a diameter less than the diameter of the sealing section and the upper end.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The inventive concepts disclosed herein generally relate to sucker rodstrings for producing oil and gas, and more particularly, but not by wayof limitation, to a polished rod having a latching section near theupper end of the polished rod with a reduced diameter on which a rodelevator can be attached.

2. Brief Description of Related Art

In the production of hydrocarbons from subsurface formations, it iscommon to use a sucker rod to lift fluids to the surface. Typical suckerrod pumps include a string of sucker rods extending from the earth'ssurface down to a downhole pump. A pump jack located on the surface isemployed to reciprocate the sucker rod string and thus the downholepump. The pump jack typically is a beam that pivots in a vertical planeand which is provided with a horse head at one end. The horse headsupports a pair of bridle cables and a carrier bar.

A polished rod is suspended from the carrier bar and extended through astuffing box. The lower end of the polished rod is attached to the upperend of the sucker rod string. The polished rod has a polished exteriorsurface to serves to form a seal with the stuffing box and thus forceformation fluid that is lifted to the earth's surface to flow fromproduction tubing to a collection conduit by which the produced fluid isconveyed to a tank battery, pipeline or other system whereby theproduced fluid is collected.

The sucker rod string is formed of a series of individual sucker rodswhich are connected to one another in an end-to-end fashion so as towork together to lift the fluid from the ground. At times, the needarises to service the well or replace or maintenance the downhole pump.To do so requires the sucker rod string be removed from the well.

Removal of the sucker rod string starts with the removal of the polishedrod. Because polished rods are manufactured with a smooth, polishedshaft having a uniform diameter, a pony rod is typically attached to theupper end of the polished rod to provide a location at which an elevatorcan be attached. Pony rods are provided with a recessed sectionconsisting of a smaller diameter than the diameter at its ends. Thisrecessed section allows the rod elevator to be attached to the pony rodso that the rod string can be lifted from the well.

After the polished rod is lifted and detached from the sucker rodstring, the remaining sucker rods in the rod string are removed withoutthe assistance of a pony rod because the sucker rods have a latchingarea for the rod elevator. Thus, only the polished rod requires the useof the pony rod to facilitate its removal from the rod string.

While the use of pony rods has long been accepted in the petroleumindustry, many inefficiencies are encountered in the use of pony rods.For example, because polished rods are manufactured in a variety ofsizes, those servicing wells must maintain an inventory of a variety ofsizes of pony rods, thereby increasing costs. More critical, however, isthe fact that the steps required to install a pony rod on a polished rodplaces services personnel in precarious positions above the well andthus exposes the service personnel to severe injury.

Therefore, a need exists for an improved polished rod that includes anintegral latching section near an upper end to provide a latching area.It is to such an improved polished rod that the inventive conceptsdisclosed herein are directed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevation view of a prior art pumping unit.

FIG. 2 is an elevation view of the prior art pumping unit of FIG. 1illustrating a pony rod attached to a polished rod.

FIG. 3 is an elevation view of the prior art polished rod.

FIG. 4 is an elevation view of a polished rod constructed in accordancewith the inventive concepts disclosed herein.

FIG. 5 is an elevation view of polished rod of FIG. 4 shown suspendedfrom a rod elevator.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Before explaining at least one embodiment of the presently disclosed andclaimed inventive concepts in detail, it is to be understood that thepresently disclosed and claimed inventive concepts are not limited intheir application to the details of construction, experiments, exemplarydata, and/or the arrangement of the components set forth in thefollowing description or illustrated in the drawings. The presentlydisclosed and claimed inventive concepts are capable of otherembodiments or of being practiced or carried out in various ways. Also,it is to be understood that the phraseology and terminology employedherein is for purpose of description and should not be regarded aslimiting.

Referring now to the drawings, and in particular FIG. 1, one version ofa conventional beam pumping unit 10 is illustrated. The pumping unit 10includes a pump jack 12 that drives a downhole reciprocating pump (notshown) located in a wellbore 14. The pump jack 12 has a walking beam 16with a horse head 18 located at one end. Activation of a primary mover20 causes the horse head 18 to deliver a reciprocal pumping stroke tothe downhole pump. A carrier bar 22 is suspended from bridle cables 24 aand 24 b which roll tangentially over the horse head 18 as itreciprocates. A string of sucker rods 26 is suspended from the carrierbar 22, and the sucker rod string 26 extends down production tubing 28to drive the pump.

A polished rod 30 is connected to the top of the sucker rod string 26.The polished rod 30 extends through a stuffing box 32 and through thecarrier bar 22. A rod clamp 34 is secured to the polish rod 30 above thecarrier bar 22 to support the sucker rod string 26 while the weight iscarried by the bridle cables 24 a and 24 b and the carrier bar 22.

Referring now to FIG. 2, one version of a prior art pony rod 36 is shownconnected to the upper end of the polished rod 30 with a coupler 38. Thepony rod 36 includes a recessed section 40. A rod elevator 41 which issupported by a rod hook 42 is shown latched to pony rod 36 at therecessed section 40 of the pony rod 36. The rod hook 42 is connected toan external hoist (not shown).

The prior art polished rod 30 is best shown in FIG. 3 as including shank43 with a threaded upper pin connector 44, and a threaded lower pinconnector 46. The shank 43 has a uniform diameter and a polished surface48 which travels slidably through the stuffing box 32 (FIG. 1) such thata hydraulic seal is maintained.

As discussed above, removal of the sucker rod string 26 from the wellbore 14 entails disconnecting the carrier bar 22 and the rod clamp 34from the polished rod 30 and attaching the pony rod 36 to the upper endof the polished rod 30 to allow the rod elevator 42 to be latched to thesucker rod string 26 and the external hoist (not shown) to be used tolift the sucker rod string 26 from the wellbore 14 so that the polishedrod 30 may be disconnected from the remainder of the sucker rod string26. As will be appreciated, the process of attaching a typical pony rodto sucker rod string prior to removal of the sucker rod string from awellbore s cumbersome and inefficient. In addition, because the upperend of the polished rod often extends a considerable height above thestuffing box, personnel are exposed to hazardous conditions during theprocess of installing a pony rod.

Referring now to FIG. 4, one embodiment of a polished rod 50 constructedin accordance with the inventive concepts disclosed herein isillustrated. The polished rod 50 includes a unitary or one piece shank52 having an upper end 54 and a lower end 56. The shank 52 may be formedof a variety of materials, such as steel and steel alloy. The upper end54 and the lower end 56 each have a diameter. A first connector 58 isformed on the upper end 54 of the shank 52, and a second connector 60 isformed on the lower end 56 of the shank 42. In one embodiment, the firstand second connectors 58 and 60 may be in the form of threaded rod pinconnectors. However, it should be appreciated that the connectors may bein a variety of forms.

The shank 52 further includes at least one sealing section 62 and alatching section 64. The sealing section 62 extends from the lower end56 of the shank 62 towards the upper end 54 of the shank 52, and thelatching section 64 is formed between the sealing section 62 and theupper end 54 of the shank 52. It will be appreciated, however, that theshank 52 may be formed to include a latching section on both the lowerend 56 and the upper end 54.

The sealing section 62 is configured to travel slidably through thestuffing box such that a hydraulic seal is maintained. To this end, thesealing section 62 has a polished surface 66 and a uniform diameterwhich is substantially equal to the diameter of the upper end 54 and thelower end 56 of the shaft 52. In one embodiment, the polished surface 66has a surface finish in a range of about 8 μin. to about 32 μin.However, it will be appreciated that a variety of surface finishes maybe utilized. In addition, it will be appreciated that the length anddiameter of the sealing section 62 may be varied, but typically thelength will be in a range of eight feet to forty feet. Finally, it willbe appreciated by those of ordinary skill in the art that a polished rodliner (not shown) may be secured about the sealing section 62 wherebythe polished rod liner forms the hydraulic seal with the stuffing box.

The latching section 64 of the shank 52 is characterized as having adiameter less than the diameter of the sealing section 62 and the upperend 54 so as to define a recessed area on the polished rod 50 on which arod elevator may latch. In one embodiment, the length of the latchingsection 64 is less than the length of the sealing section 62, and thelatching section 62 has a generally cylindrical cross-section to permitlatching of a rod elevator to the latching section 62.

In use, the polished rod 50 is connected to the upper end of the suckerrod string 26 in a manner similar to that described above in relation tothe polished rod 30. The polished rod 50 extends through the stuffingbox 32 and through the carrier bar 22. The rod clamp 34 is secured to aselected location on the sealing section 62 of the shank 52 above thecarrier bar 22 to support the sucker rod string 26 while the weight iscarried by the bridle cables 24 a and 24 b and the carrier bar 22.

With reference to FIG. 5, removal of the sucker rod string 26 simplyrequires disconnecting the carrier bar 22 and the rod clamp 34 from thepolished rod 30 and attaching the rod elevator 41, which is connected tothe rod hook 42 and the external hoist (not shown), to the latchingsection 64 of the shank 52 Due to the presence of the polished rod 50,the rod elevator 41 attaches directly to the polished rod 50 rather thanto a pony rod that must first be installed. Thus, employment of thepolished rod 50 eliminates the need to insert the pony rod 26 into thesucker rod string before the polished rod 50 and the sucker rod string26 are lifted from the wellbore 12.

From the above description, it is clear that the present inventiveconcept is well adapted to carry out the objects and to attain theadvantages mentioned herein as well as those inherent in the invention.While exemplary embodiments of the invention have been described forpurposes of this disclosure, it will be understood that numerous changesmay be made which will readily suggest themselves to those skilled inthe art and which are accomplished within the spirit of the inventiveconcept disclosed and claimed herein.

1. A polished rod for supporting a sucker rod string, comprising: a onepiece shank having an upper end and a lower end, the upper end and lowerend each having a diameter; a first connector formed on the upper end ofthe shank; and a second connector formed on the lower end of the shank,wherein the shank has a sealing section extending from the lower endtoward the upper end, the sealing section having a polished surface anda uniform cylindrical diameter substantially equal to the diameter ofthe upper end and the lower end of the shank, wherein the shank has alatching section formed between the sealing section and the upper end,the latching section of the shank having a diameter less than thediameter of the sealing section and the upper end.
 2. The polished rodof claim 1 wherein the length of the latching section is less than thelength of the sealing section.
 3. The polished rod of claim 1 whereinthe latching section has a cylindrical cross-section.
 4. The polishedrod of claim 1 wherein the polished surface has a surface finish in arange of about 8 μin. to about 32 μin.
 5. A polished rod for supportinga sucker rod string, comprising: a one piece shank having an upper endand a lower end, the upper end and lower end each having a diameter; afirst threaded rod pin formed on the upper end of the shank; and asecond threaded rod pin formed on the lower end of the shank, whereinthe shank has a sealing section extending from the lower end toward theupper end, the sealing section having a polished surface and a uniformcylindrical diameter substantially equal to the diameter of the upperend and the lower end of the shank, wherein the shank has a latchingsection formed between the sealing section and the upper end, thelatching section of the shank having a diameter less than the diameterof the sealing section and the upper end.
 6. The polished rod of claim 5wherein the length of the latching section is less than the length ofthe sealing section.
 7. The polished rod of claim 5 wherein the latchingsection has a cylindrical cross-section.
 8. The polished rod of claim 5wherein the polished surface has a surface finish in a range of about 8μin. to about 32 μin.